Homopolymers of tetrahydrofuran (THF), also known as polytetramethylene ether glycols (PTMEG), are well known for use as soft segments in polyurethanes and other elastomers. These homopolymers impart superior dynamic properties to polyurethane elastomers and fibers. Copolymers of THF and at least one other cyclic ether, also known as copolyether glycols, are known for use in similar applications, particularly where the reduced crystallinity imparted by the other cyclic ether may improve certain dynamic properties of a polyurethane which contains such a copolymer as a soft segment. Among the other cyclic ethers used for this purpose are ethylene oxide and propylene oxide.
Copolymers of THF and cyclic ether are well known in the art. Their preparation is disclosed, for example, by Pruckmayr in U.S. Pat. No. 4,139,567 and U.S. Pat. No. 4,153,786. Such copolymers can be prepared by any of the known methods of cyclic ether polymerization, described for instance in “Polytetrahydrofuran” by P. Dreyfuss (Gordon & Breach, N.Y. 1982). Such polymerization methods include catalysis by strong proton or Lewis acids, by heteropoly acids, as well as by perfluorosulfonic acids or acid resins. In some instances it may be advantageous to use a polymerization promoter, such as a carboxylic acid anhydride, as disclosed in U.S. Pat. No. 4,163,115. In these cases the primary polymer products are diesters, which need to be hydrolyzed in a subsequent step to obtain the desired polyether glycols.
Other methods for manufacturing copolyether glycols are known in the art, such as for example as shown in U.S. Pat. Nos. 4,192,943; 4,228,272; 4,564,671; and 4,585,592; and in published patent applications WO 03/076453 and WO 03/076494. For example, U.S. Pat. No. 4,564,671 discloses a process for polymerization of THF with a 1,2-alkylene oxide in the presence of a compound containing reactive hydrogen and a fixed-bed clay catalyst in which less than 30% by weight of a mixture of THF, 1,2-alkylene oxide, and a compound containing reactive hydrogen is added to the reaction mixture, which is then recycled to the reactor. U.S. Pat. No. 4,728,722 discloses such polymerization batchwise with a 1,2-alkylene oxide in the presence of compounds containing reactive hydrogen over a bleaching earth or zeolite catalyst, the 1,2-alkylene oxide being fed to the reaction mixture in such a manner that the concentration of the 1,2-alkylene oxide in the reaction mixture is kept below 2% by weight during the polymerization. U.S. Pat. No. 5,268,345 discloses polymerization of THF with ethylene oxide when montmorillonite catalyst which has been regenerated by the process disclosed therein is used. U.S. Pat. No. 4,192,943 discloses that copolyether glycol based on THF and alkylene oxides varies with the method of production. U.S. Pat. No. 4,677,231 discloses use of diluent or solvent for purification of copolyether glycol having a normal molar incorporation of alkylene oxide manufactured in a polymerization process utilizing a normal concentration of alkylene oxide as a feedstock component.
U.S. Pat. Nos. 4,120,903 and 4,139,567 disclose preparation of copolyether glycols by copolymerizing THF and an alkylene oxide or cyclic acetal over catalyst comprising a polymer containing fluorosulfonic acid groups and with water or an alkanediol as a chain terminator.
A number of publication families describe fluorosulfonic acid resins and their use as catalyst material for polymerization reactions. Among these are U.S. Pat. Pub. 2009/0118456, disclosing use of perfluorinated ion-exchange polymer containing pendant sulfonic acid and carboxylic acid groups; U.S. Pat. No. 6,040,419, disclosing use of fluorinated sulfonic acid-containing polymer containing at least 0.05 equivalents of fluorinated sulfonic acid group per kg of polymer; WO 95/19222, disclosing use of perfluorinated ion-exchange polymer containing pendant sulfonic acid and carboxylic acid groups; and U.S. Pat. No. 5,118,869, disclosing use of a blend of a fluorinated resin containing sulfonic acid groups and a fluorinated resin containing carboxylic acid groups. Likewise, U.S. Pat. No. 5,403,912 discloses use of a perfluorinated resin sulfonic acid consisting of a backbone of fluoropolymer. U.S. Pat. Pub. 2008/0071118 discloses use of a resin having a perfluoroalkylsulfonic acid group as a side chain in a list of possible catalysts. U.S. Pat Pub. 2003/176630 discloses use of polymers comprising alpha-fluorosulfonic acids.
None of the above publications teach the production of polyether or copolyether glycols by polymerization of a reaction mixture comprising at least one tetrahydrofuran or at least one tetrahydrofuran and at least one other cyclic ether, for example, an alkylene oxide, in the presence of a particular perfluorosulfonic acid resin as catalyst, the perfluorosulfonic acid resin being a copolymer of tetrafluoroethylene (TFE) or chlorotrifluoroethylene (CTFE) and a monomer of the formula CF2═CF—O—CF2—CF2—SO2F. A simple, economical, improved process for manufacturing polyether and copolyether glycols by polymerization of a reaction mixture comprising tetrahydrofuran or tetrahydrofuran and at least one other cyclic ether is provided by the present invention.